Absolute Bone Conduction Test

From Otolaryngology Online

Absolute bone conduction test:

It is a variant of Schwabach test. In Schwabach test the external auditory canal is not occluded. This test is performed to identify sensorineural hearing loss. In this test the hearing level of the patient is compared to that of the examiner. The examiner's hearing is assumed to be normal. In this test the vibrating fork is placed over the mastoid process of the patient after occluding the external auditory canal. As soon as the patient indicates that he is unable to hear the sound anymore, the fork is transferred to the mastoid process of the examiner after occluding the external canal. In cases of normal hearing the examiner must not be able to hear the fork, but in cases of sensori neural hearing loss the examiner will be able to hear the sound, then the test is interpreted as ABC reduced. It is not reduced in cases with normal hearing.

This test is ideally performed using 256, 512 and 1024 Hz tuning forks. These frequencies are used because they fall within the normal speech frequency range.